External gear machine

ABSTRACT

The invention relates to an external gear machine ( 1 ) in particular an external gear pump or an external gear motor, having at least two gears ( 3, 4 ) that mesh with each other in external engagement, wherein the gears ( 3, 4 ) are surrounded by a housing ( 10 ), wherein one gear ( 4 ) has at least one bearing journal ( 7, 8 ) and the other gear ( 3 ) has a driving or driven journal ( 5 ), which are in each case mounted in a bearing bushing ( 38 ) so as to respectively be rotatable about a rotation axis ( 13, 14 ), wherein a bearing sleeve pp with an anti-twist element is arranged in the bearing bushing ( 38 ). In order to improve the external gear machine, in particular with regard to the materials that can be used for producing the bearing bushings and/or the service life, the anti-twist element of the bearing sleeve is arranged in a through-hole of the bearing bushing and is combined with a filter device and/or throttle device via which a working medium of the external gear machine ( 1 ) reaches the bearing sleeve.

BACKGROUND OF THE INVENTION

The invention relates to an external gear machine, in particular anexternal gear pump or an external gear motor, having at least two gearsthat mesh with each other in external engagement, wherein the gears areenclosed by a housing, wherein the one gear comprises at least onebearing journal and the other gear comprises a driving or drivenjournal, which are each supported in a respective bearing bush so thatthey are each rotatable about a respective axis of rotation, wherein abearing sleeve having a torsional lock is arranged in the bearing bush.

The unexamined German application DE 10 2012 216 254 A1 discloses anexternal gear machine, in particular a pump or a motor, having alow-pressure connection and a high-pressure connection situated axiallyopposite one another, having at least two gears that mesh with eachother in external engagement, wherein the gears are enclosed by ahousing and the one gear comprises a shaft journal and the other gearcomprises a driving or driven shaft, which are each supported in arespective bearing bore of a bearing bush, having a substantiallyrotationally symmetrical cross-section, so that they are each rotatableabout a respective axis of rotation, wherein the bearing bushes arereceived in corresponding seating apertures of the housing, wherein thebearing bushes are composed of aluminum or an aluminum alloy and/or thehousing is composed of grey cast iron, wherein the two radially adjacentbearing bushes are each connected to one another to form a double-glandbearing, wherein bearing sleeves, having an axial slot and in which theshaft journal and the driving or driven shaft are rotatably supported,are inserted into the bearing bores of the bearing bushes, wherein thebearing sleeves comprise one or two torsional locking projections, whichextend into a locking aperture opening radially into the bearing bore.

SUMMARY OF THE INVENTION

The object of the invention is to improve an external gear machine, inparticular an external gear pump or an external gear motor, having atleast two gears that mesh with each other in external engagement,wherein the gears are enclosed by a housing, wherein the one gearcomprises at least one bearing journal and the other gear comprises adriving or driven journal, which are each supported in a respectivebearing bush so that they are each rotatable about a respective axis ofrotation, wherein a bearing sleeve having a torsional lock is arrangedin the bearing bush, particularly with a view to the materials than canbe used for manufacture of the bearing bushes and/or the service life ofthe external gear machine.

The object is achieved, in the case of an external gear machine, inparticular an external gear pump or an external gear motor, having atleast two gears that mesh with each other in external engagement,wherein the gears are enclosed by a housing, wherein the one gearcomprises at least one bearing journal and the other gear comprises adriving or driven journal, which are each supported in a respectivebearing bush so that they are each rotatable about a respective axis ofrotation, wherein a bearing sleeve having a torsional lock is arrangedin the bearing bush, in that the torsional lock of the bearing sleeve isarranged in a through-hole in the bearing bush and is combined with afilter device and/or restriction device, through which a working mediumof the external gear machine reaches the bearing sleeve. The bearingsleeves in the bearing bushes together with the journals rotatablyarranged therein represent plain bearings. The bearing sleeves are thenalso referred to as plain bearing sleeves. The plain bearing sleeves areadvantageously pressed into an aluminum bearing bush. The external gearmachine is preferably used as an external gear pump in a WHR system, thecapital letters WHR standing for the English term Waste Heat Recovery.The WHR system serves for recovering energy from an exhaust gas of acombustion engine in a drivetrain of a motor vehicle. In order toutilize the waste heat from the exhaust gas, a heat exchanger, whichtransmits the heat from the exhaust gas to a working medium flowing in aheat cycle, is arranged in an exhaust tract of the combustion engine.The working medium in the heat cycle drives an expansion engine. Theheat cycle is a thermodynamic working cycle or steam power cycle, whichis also referred to as a Rankine cycle or Clausius-Rankine cycle. Acontinuous-flow machine, for example a turbo machine, or apositive-displacement machine, for example a piston engine, a screwmachine or a scroll machine, is used as expansion engine. A condenserand an evaporator are also arranged in the working cycle. The externalgear pump is arranged in the working cycle between the condenser and theevaporator. A low-viscosity medium, such as an ORC fluid, is preferablyused as working medium in the working cycle. The letters ORC stand forthe English term Organic Rankine Cycle. Examples of ORC fluids areethanol or cyclopentane. In automotive applications the use of arefrigerant, such as is used air-conditioning systems, has provedadvantageous. The refrigerant has adequate thermodynamic characteristicsand is moreover not inflammable. One disadvantage, however, is that thelow-viscosity fluid or medium, for example ethanol, has few, if any,lubricating properties. For this reason, in tests and analyses conductedin the course of the present invention adaptations were made aimed atreducing the bearing stresses. In doing this, for example, the bearingplay was reduced and/or the shaft diameter or journal diameter wasincreased. With the larger shaft diameter or journal diameter, however,a more stable bearing backing is needed. More stable bearing backings orbearing bushes are formed from a steel material, for example, ratherthan the aluminum material. Combining the torsional lock of the bearingsleeve with the filter device and/or restriction device creates adual-function part. The dual-function part can serve firstly to reducethe compression of the bearing sleeve in the bearing bush, since anunwanted torsion of the bearing sleeve, resulting from temperatureconditions in the bearing and the mechanical bearing stress, forexample, is mechanically blocked. Furthermore, the dual-function partcan serve for ducting working medium through the bearing bush to thebearing sleeve. The working medium can serve to dissipate frictionalheat occurring in the operation of the plain bearing. One particularadvantage is that the working medium additionally delivered through therestriction device and/or filter device can improve the build-up of ahydrodynamic lubricating wedge in the plain bearing. Here the filterdevice and/or restriction device combined with the torsional lock in thedual-function part prevents an unwanted ingress of particles, especiallymetal chips, into the plain bearing.

A preferred exemplary embodiment of the external gear machine ischaracterized in that the filter device and/or restriction devicecombined with the torsional lock comprises a gap filter for the workingmedium. The gap filtration firstly keeps particles of a risky size awayfrom restriction passages, especially restriction bores, in the bearingsleeve. Furthermore, the gap filtration affords a self-cleaning effect,since the particles are kept outside the bearing bush in the flowingworking medium. This means that in a circulating flow the particles canbe purposely flushed away with the working medium delivered through theexternal gear machine.

A further preferred exemplary embodiment of the external gear machine ischaracterized in that the filter device and/or restriction devicecombined with the torsional lock comprises a body having at least oneflattening, which is arranged in the through-hole in the bearing bush.The body advantageously has substantially the shape of a straightcircular cylinder. The flattening on the body allows the passage ofworking medium. The through-hole in the bearing bush is designed as abore, for example. The body of the filter device and/or restrictiondevice combined with the torsional lock, for example, is screwed intothe through-hole in the bearing bush. The flattening is thenadvantageously formed as a surface on the engagement thread of the body.

A further preferred exemplary embodiment of the external gear machine ischaracterized in that the body comprises a torsional lock point at anend facing the bearing sleeve, and a spacer with a filter head at an endremote from the bearing sleeve. The torsional lock point represents apin, which can be turned into the bearing sleeve, in order to securethis mechanically against rotation in the bearing bush. The torsionallock point is advantageously integrally connected to the body. Thespacer is connected to the filter head by a stepped offset. In screwingin or tightening the body, the filter device and/or restriction devicecombined with the torsional lock is firmly tightened onto the spacer. Adesired gap filtration can be set by way of the dimensions or size, inparticular the height, of the spacer. The spacer has a height of lessthan 0.8 millimeter, for example. The spacer and the filter head serveto present a gap for the gap filter. The filter head is advantageouslyintegrally connected to the body by way of the spacer.

A further preferred exemplary embodiment of the external gear machine ischaracterized in that two radially adjacent bearing bushes are connectedto one another to form a double-gland bearing, wherein the filter deviceand/or restriction device combined with the torsional lock comprises aconnecting member, which connects two torsional locking elements to oneanother and serves for fastening the filter device and/or restrictiondevice combined with the torsional lock to the double-gland bearing. Thethrough-hole is preferably an opening or two openings, which is/arecombined with a locating slot, described below, to represent supplychannels. The connecting of two radially adjacent bearing bushes to forma double-gland bearing is known in the art. The term radial relates tothe axes of rotation of the associated plain bearings. Radial signifiestransversely to the axes of rotation. The two torsional locking elementsare advantageously integrally connected to one another by the connectingmember. This facilitates considerably the handling and assembly of thefilter device and/or restriction device combined with the torsionallock. The torsional locking elements, which are preferably integrallyconnected to the connecting member, are at their free endsadvantageously designed as points, which in pressing the connectingmember into the locating slot are pushed into the two bearing sleeves astorsional locking.

A further preferred exemplary embodiment of the external gear machine ischaracterized in that the double-gland bearing comprises a locatingslot, which extends between two working medium supply channels throughthe bearing bushes to the respective bearing sleeve and serves toreceive the connecting member with the torsional locking elements. Thelocating slot is made as a milled slot, for example. A locating gap ormilled gap, at least over a part of the length of the locating slot ormilled slot, has a fit size for pressing in the connecting member. Herethe connecting member advantageously represents a type of taper key,which is driven into the locating slot or milled slot. At its two endsthe locating slot is advantageously made somewhat wider, so as torepresent the supply channels. The supply channels preferably run alongthe torsional locking elements. The supply channels easily afford apreferably filtered inflow in the direction of the two bearing sleeves

A further preferred exemplary embodiment of the external gear machine ischaracterized in that an edge area is bent off from the connectingmember which, at least in the area of the supply channels, exercises agap filter function for the working medium. The connecting memberpreferably has substantially the shape of an elongated parallelepiped,which is pressed like a taper key into the locating slot of thedouble-gland bearing. From the underside of the connecting member facingthe double-gland bearing, the torsional locking elements extend towardsthe bearing sleeves in the double-glad bearing. On the upper side of theconnecting member remote from the double-glad bearing, the edge area isbent off. The edge area is bent off by flanging, for example. An anglebetween the bent-off edge area and the connecting member is preferablysubstantially ninety degrees. In order to represent a gap filterfunction, the bent-off edge area, at least in the area of the supplychannels, is separated by a distance from the double-gland bearing suchthat a filter gap is produced for the working medium. This is an easyway of preventing an unwanted inflow of particles, for example metalchips, towards the bearing sleeves. A pressing force used to press theconnecting member in serves to set the gap height of the filter gap.

A further preferred exemplary embodiment of the external gear machine ischaracterized in that the edge area bent off from the connecting memberbetween the supply channels represents a limit stop for the filterdevice and/or restriction device combined with the torsional lock. Toform the limit stop, the bent-off edge area, for example the flange, isbent deeper in a middle area. The limit stop serves to facilitatefitting of the filter device and/or restriction device combined with thetorsional lock, especially when pressing the connecting member into thelocating slot. A height of the middle or more heavily bent flange is aneasy way of defining the height of the gap filter. In the area of thesupply channels the bent-off edge area is not more heavily bent, inorder to maintain the gap filter function.

A further preferred exemplary embodiment of the external gear machine ischaracterized in that at least one cooling duct, which extends from thethrough-hole or from the supply channels in the bearing bush to at leastone restriction passage in the bearing sleeve, is provided between thebearing sleeve and the bearing bush. The restriction passage in thebearing sleeve is designed as a restriction bore, for example. In theoperation of the external gear machine, the heat generated in the plainbearing or in the plain bearings is dissipated outwards via the bearingbush or the bearing bushes. Aluminum bearing bushes or double-glandbearings have a better heat dissipation than, for example, steelbushings. In the tests and analyses conducted in the course of thepresent invention, at least one cooling duct, which is designed as ascavenging groove, was incorporated into the plain bearing, preferablyinto the bearing bush, for additional heat dissipation. The coolingduct, especially the scavenging groove, has a very small restrictiondiameter at its outlet into the bearing sleeve, that is to say at therestriction passage. The restriction diameter is 0.8 millimeter, forexample. The filter device and/or restriction device combined with thetorsional lock serves to prevent particles, in particular metal chips,being able to reach the restriction passage. An unwanted blockage of therestriction passage, which is also referred to as the scavenging bore,is thereby prevented.

The invention further relates to a filter device and/or restrictiondevice combined with a torsional lock, a bearing bush and/or adouble-gland bearing for an external gear machine as previouslydescribed. Said parts are marketable separately. The bearing bush ordouble-gland bearing is advantageously formed from a highly thermallyconductive material, such as aluminum. This improves the dissipation ofthe frictional heat occurring in the operation of the external gearmachine and avoids unwanted over-stressing of the plain bearing or plainbearings. Furthermore, the bearing bush or double-gland bearing isadvantageously formed from a lightweight material, such as aluminum.This makes the external gear machine lighter. The aluminum materialmoreover affords the advantage that it is easy to machine, especially inchip-forming metal machining. The bearing bush or double-gland bearingis advantageously produced as a blank in a die casting process. Thisaffords the advantage that some processing steps can be eliminated orshifted directly to the die casting process.

The invention may also relate to a method for the operation and/ormanufacture and assembly of an external gear machine as previouslydescribed. For example, during a process of running in the external gearmachine, material abrasion to the gear tooth crests of the gears of theexternal gear machine of a housing inner wall, metal chips may beproduced in the external gear machine, which could block the restrictionpassage. This is reliably prevented by the filter device and/orrestriction device combined with the torsional lock.

Further advantages, features and details of the invention emerge fromthe following description, in which various exemplary embodiments aredescribed in detail, referring to the drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

In which:

FIG. 1 shows a schematic representation of the external gear machinewith a bearing arrangement, which comprises four plain bearings;

FIG. 2 shows a plain bearing from FIG. 1 in a section through a bearingbush with a torsional lock for the bearing sleeve, wherein the torsionallock is combined with a filter device and/or restriction device;

FIG. 3 shows the enlarged representation of a detail III from FIG. 2;

FIG. 4 shows a perspective representation of the filter device and/orrestriction device combined with the torsional lock from FIGS. 1 and 2;

FIG. 5 shows the representation of a section along the line V-V in FIG.6 through a double-gland bearing with a torsional lock for two bearingsleeves, wherein the torsional lock is combined with a filter deviceand/or restriction device;

FIG. 6 shows the double-gland bearing from FIG. 5, represented in a topview;

FIG. 7 shows the view of a section along the line VII-VII in FIG. 5;

FIG. 8 shows a detail VIII from FIG. 7;

FIG. 9 shows a perspective representation of the filter device and/orrestriction device combined with the torsional lock from FIG. 5, and

FIGS. 10-14 show representations similar to those in FIGS. 5 to 9,according to a further exemplary embodiment, in which a connectingmember of the filter device and/or restriction device combined with thetorsional lock represents a limit stop.

DETAILED DESCRIPTION

FIG. 1 shows a schematic representation of an external gear machine 1with a first gear 3 and second gear 4 in a simplified longitudinalsection. The externally toothed gears 3, 4 mesh with each other inexternal engagement.

In FIG. 1 the first gear 3 is rotationally fixed on its left-hand faceto a journal 5. If the external gear machine 1 is designed as anexternal gear pump, the first gear 3 can be driven by the journal 5,which is then also referred to as a drive journal 5. On its right-handside in FIG. 1 the first or driving gear is rotationally fixed to thebearing journal 6.

The second gear 4 in FIG. 1 laterally has two bearing journals 7, 8, towhich the second gear 4 is rotationally fixed. The two gears 3, 4 arerotatably supported in a housing 10 by means of the journals 5, 6 and 7,8. The first gear 3 is rotatable about a first axis of rotation 13 bymeans of the drive journal 5 and the bearing journal 6. The second ordriven gear 4 is rotatable about a second axis of rotation 14, which isparallel to the first axis of rotation 13, by means of the bearingjournals 7, 8.

On its left-hand side in FIG. 1, the housing 10 is bounded by a firsthousing cover 11, and on its right-hand side in FIG. 1 by a secondhousing cover 12. A housing body 15 of the housing 10 is arrangedbetween the housing covers 11, 12.

The first housing cover 11 is fixed to the housing body 15 by fixingmeans 16, 17. The second housing cover 12 is fixed to the housing body15 by fixing means 18, 19. The fixing means 16 to 19 are dowel pins, forexample. The housing covers 11, 12 are connected by means of threadedbolts 81 and washers 82.

In FIG. 1 a first housing gasket 21 is arranged between the firsthousing cover 11 and the housing body 15. In FIG. 1 a second housinggasket 22 is arranged between the second housing cover 12 and thehousing body 15.

In FIG. 1 a radial shaft seal ring 24 serves for sealing a passagethrough the first housing cover 11 in which the drive journal 5 rotates.The radial shaft seal ring 24 is externally fitted in a known mannerinto an annular space which extends around the drive journal 5.

In FIG. 1 a bearing arrangement 25 serves to support the two gears 3, 4in the housing 10. The bearing arrangement 25 comprises two bearings 26,27 for supporting the first gear 3. The bearing 25 comprises two furtherbearings 28, 29 for supporting the second gear 4.

Two axial field seals 31, 32, which serve for sealing between thebearings 26, 27 and the housing covers 11, 12, are assigned to thebearings 26 and 27. Two axial field seals 33, 34, which serve forsealing between the bearings 28, 29 and the housing covers 11, 12, areassigned to the bearings 28, 29.

The axial field seals 31 and 33 are advantageously combined in onecomponent. The axial field seals 32 and 34 are likewise advantageouslycombined in one component. The bearings 26 and 28 are then sealed by thecombined axial field seal 31, 33. The bearings 27 and 29 are then sealedby the combined axial field seal 32, 34.

The bearings 26 to 29 of the external gear machine 1 are designed asplain bearings, each having a bearing bush. A bearing sleeve is arrangedin the bearing bush. Two radially adjacent bearing bushes mayadvantageously be connected to one another to form a double-glandbearing.

FIG. 2 represents a plain bearing 36 having a bearing bush 38 incross-section. The bearing bush 38 in FIG. 2 has a through-hole 39 atthe top. The through-hole 39 takes the form of a radial bore, forexample.

A bearing sleeve 40 is pressed into the bearing bush 38. Two arrows 41,42 in FIG. 2 indicate a restriction passage, which takes the form of arestriction bore. The working medium, with which the external gearmachine (1 in FIG. 1) is operated, reaches the bearing sleeve 40 via thethrough-hole 39 in the bearing bush 38. The working medium passes fromthe through-hole 39 to the restriction bore 41, 42 via at least onecooling duct 54. The through-hole 39, preferably formed as a bore, isconnected to a high-pressure duct of the external gear machine, alsoreferred to in brief as a pump, or to the high-pressure duct arranged.This connection or arrangement serves to supply the pump and the plainbearings with fresh medium.

The working medium passes through the restriction bore 41, 42 to theinside of the bearing sleeve 40, where it advantageously improves thebuild-up of a hydrodynamic lubricating wedge of the plain bearing.Furthermore, by flushing the plain bearing with the working medium heatcan be dissipated from the plain bearing 36. For this reason, therestriction bore 41, 42 is also referred to as a scavenging bore. Thenecessary flushing quantity may be determined by the size of therestriction bore 41, 42. The restriction bore 41, 42 has a diameter of0.8 millimeter, for example.

A dual-function part 43 is arranged in the through-hole 39 in thebearing bush 38. The dual-function part 43, as can be seen in FIG. 3,combines a torsional lock 44 for the bearing sleeve 40 with a filterdevice and/or restriction device 45 for the working medium entering thethrough-hole 39. The filter device/and/or restriction device combinedwith the torsional locking device comprises a body 46, whichsubstantially has the shape of a straight circular cylinder with anexternal thread.

From the body 46 a pin having a torsional lock point 47 extendsdownwards in FIG. 3. The body 46 is screwed into the through-hole 39 inthe bearing bush 38, so that the torsional lock point 47 is pressed outinto the bearing sleeve 40. The bearing sleeve 40 is thereby held inposition, secured against torsion, in the bearing bush 38.

It will be seen in FIGS. 3 and 4 that the body 46 of the dual-functionpart 43 is integrally connected to a filter head 49 by a spacer 48. Thespacer 48 has substantially the shape of a circular disk with aflattening, not further identified, which merges into a flattening 50 ofthe body 46.

The spacer 48 in combination with the filter head 49 serves to representa filter gap 51, 52. In FIG. 3 particles, which collect in front of thefilter gap 51, 52, are indicated at 53. A suitable size, in particularthe height, of the filter gap 51, 52, prevents the particles 53 passingthrough the through-hole 39 in the direction of the bearing sleeve 40.The working medium passes without the particles 53 through the filtergap 51, 52 along the flattening 50 into the cooling duct 54.

FIGS. 4 and 5 show two exemplary embodiments of two plain bearings 56,57, in which two bearing bushes 58, 59 are combined in a double-glandbearing 60. A bearing sleeve 61 is arranged in the bearing bush 58. Abearing sleeve 62 is arranged in the bearing bush 59. The two bearingbushes 58, 59 are integrally connected to one another by thedouble-gland bearing 60.

A dual-function part 63, in which a torsional lock is combined with afilter device and/or restriction device 86, is assigned to thedouble-gland bearing 60. Here too, the torsional lock 63 is fitted intothe high-pressure area of the external gear machine, also referred to inbrief as a pump, in order to supply the plain bearings with fresh mediumfrom the high pressure. The torsional lock comprises two torsionallocking elements 66,67, which are integrally connected to one another bya connecting member 65. At a free end, the bottom end in FIG. 5, thetorsional locking element 66 has a point 68, which is pressed into thebearing sleeve 61 to secure it against torsion. Similarly, at a freeend, the bottom end in FIG. 5, the torsional locking element 67 has apoint 69, which is pressed into the bearing sleeve 62 to secure itagainst torsion.

The dual-function part 63 is pressed or jammed with the connectingmember 65 into a locating slot 70. The locating slot 70 takes the formof a milled slot, for example, and extends between two supply channels71, 72. The supply channel 71 runs along the torsional locking element66 to the bearing sleeve 61. The supply channel 72 runs along thetorsional locking element 67 to the bearing sleeve 62. The supplychannels 71, 72 open into cooling ducts 73, 74. The cooling duct 73connects the supply channel 71 to a restriction passage 75. The coolingduct 74 connects the supply channel 72 to a restriction passage,indicated by arrows 76, 77.

The cooling ducts 73, 74, as will be seen in particular in FIGS. 5 and6, are designed as helical scavenging grooves 79, 80. The helicalscavenging grooves 79, 80 are introduced radially into the bearingbushes 58, 59 and serve to carry the working medium of the external gearpump (1 in FIG. 1). The cooling of the bearing sleeves 61, 62 is therebysignificantly improved. The working medium from the helical scavenginggrooves 79, 80 passes through the restriction passages 75, 76, 77 to theinside of the bearing sleeves 61, 62, where it serves to build up thehydrodynamic lubricating wedge in the plain bearings 56, 57.

An edge area 85 remote from the double-gland bearing 60 in FIG. 5 isbent off from the connecting member 65 in order to represent a gapfilter of the filter device and/or restriction device 86. A gap heightfor the gap filtration is indicated by arrows 87, 88 in FIG. 8.Particles, the unwanted ingress of which into the helical scavenginggrooves 79, 80 is prevented by the filter device and/or restrictiondevice 86, are indicated at 90,

In the assembly process the connecting member 65 is pressed into thelocating slot 70. The locating slot 70 has a press-fit over its lengthfor pressing in the connecting member 65. The locating slot 70 isdesigned somewhat wider close to its two ends, in order to form thesupply channels 71, 72.

It can be seen in FIG. 9 that the two points 68, 69 are integrallyconnected to the bent-off edge area 85 by the connecting member 65. Toform the bent-off edge area 85, the connecting member 65 is flanged onits upper edge. The gap height (87, 88 in FIG. 8) can be set by way ofthe pressing force used to press in the connecting member 65 ofwedge-shaped cross-section.

The exemplary embodiment represented in FIGS. 10 to 14 very largelycorresponds to the exemplary embodiment represented in FIGS. 5 to 9. Forthis reason, the same reference numerals are used to denote identical orsimilar parts. In order to avoid repetition, reference is made to thepreceding description of FIGS. 5 to 9. Only the differences between thetwo exemplary embodiments are examined below

In the exemplary embodiment represented in FIGS. 10 to 14 the edge area85 of the connecting member 65, bent-off as flanging, is bent deeper, inorder to represent a limit stop when fitting the dual-function part 63.This means that the gap height no longer depends on the pressing forcewhen pressing the connecting member 65 into the locating slot 70, aspreviously described. The height of the more heavily bent flanging inthe middle portion 100 serves to set or determine the gap height (87, 88in FIG. 13). In two end portions 101, 102 the edge area 85 is separatedby the gap height (87, 88 in FIG. 13) from the double-gland bearing 67,in order to represent the gap filter function.

1. An external gear machine (1), having at least first and second gears(3,4) that mesh with each other in external engagement, wherein thegears (3,4) are enclosed by a housing (10), wherein the second gear (4)comprises at least one bearing journal (7,8) and the first gear (3)comprises a driving or driven journal (5), wherein the bearing journaland the driven journal are supported in respective bearing bushes(38;58,59) so that the bearing journal and the driven journal arerotatable about respective axes of rotation (13,14), wherein bearingsleeves (40;61,62) having respective torsional locks (44;65,66) arearranged in respective ones of the bearing bushes (38;58,59),characterized in that the torsional lock (44;65,66) of each of thebearing sleeves (40;61,62) is arranged in a through-hole (39;70) in theassociated bearing bush (38;58,59) and is combined with a filter deviceand/or restriction device (45;86) through which a working medium of theexternal gear machine (1) reaches the bearing sleeve (40;61,62).
 2. Theexternal gear machine as claimed in claim 1, characterized in that thefilter device and/or restriction device (45;86) combined with thetorsional lock (44;65,66) comprises a gap filter for the working medium.3. The external gear machine as claimed in claim 1, characterized inthat the filter device and/or restriction device (45) combined with thetorsional lock (44) comprises a body (46) having at least one flattening(50), which is arranged in the through-hole (39) in the bearing bush(38).
 4. The external gear machine as claimed in claim 3, characterizedin that the body (46) comprises a torsional lock point (47) at an endfacing the bearing sleeve (40), and a spacer (48) with a filter head(49) at an end remote from the bearing sleeve (40).
 5. The external gearmachine as claimed in claim 1, characterized in that two radiallyadjacent bearing bushes (58,59) are connected to one another to form adouble-gland bearing (60), wherein the filter device and/or restrictiondevice (86) combined with the torsional lock comprises a connectingmember (65), which connects two torsional locking elements (66,67) toone another and serves for fastening the filter device and/orrestriction device (86) combined with the torsional lock to thedouble-gland bearing (60).
 6. The external gear machine as claimed inclaim 5, characterized in that the double-gland bearing (60) comprises alocating slot (70), which extends between two working medium supplychannels (71,72) through the bearing bushes (58,59) to the respectivebearing sleeve (61,62) and serves to receive the connecting member withthe torsional locking elements (66,67).
 7. The external gear machine asclaimed in claim 5, characterized in that an edge area (85) is bent offfrom the connecting member (65) which, at least in the area of thesupply channels (71,72), exercises a gap filter function for the workingmedium.
 8. The external gear machine as claimed in claim 7,characterized in that the edge area (85) bent off from the connectingmember (65) between the supply channels (71,72) represents a limit stop(100) for the filter device and/or restriction device (86) combined withthe torsional lock.
 9. The external gear machine as claimed in claim 6,characterized in that at least one cooling duct (54;73,74), whichextends from supply channels (71,72) in the bearing bush (38;58,59) toat least one restriction passage (41,42;75,76,77) in the bearing sleeve(40;61,62), is provided between the bearing sleeve (40;61,62) and thebearing bush (38;58,59).
 10. (canceled)
 11. The external gear machine asclaimed in claim 1, characterized in that at least one cooling duct(54;73,74), which extends from the through-hole (39;70) in the bearingbush (38;58,59) to at least one restriction passage (41,42;75,76,77) inthe bearing sleeve (40;61,62), is provided between the bearing sleeve(40;61,62) and the bearing bush (38;58,59).